This invention relates to medical injectors, and syringes, syringe interfaces, syringe adapters and syringe plungers for use therewith. More particularly, the present invention relates to front-loading medical injectors, and syringes, syringe interfaces, syringe plungers and adapters for use with new or existing medical injectors wherein a syringe of special construction is mountable upon and removable from the injectors by a releasable mechanism.
Medical injectors and syringes for injecting contrast media into a patient for imaging biological structures are known in the art. For example, U.S. Pat. No. 4,677,980, issued to D. M. Reilly et al. on Jul. 7, 1987, and entitled “Angiographic Injector and Angiographic Syringe for Use Therewith,” which is assigned to the same Assignee as the subject application, discloses an angiographic injector apparatus. The apparatus is designed for injecting contrast media into the vascular system of an animal, in which syringes are rear-loaded into a pressure jacket of the injector. More specifically, the apparatus comprises a rotatable turret which carries a pair of the pressure jackets and which is rotatable so that when one of the pressure jackets, into which a syringe has been rear-loaded, is in an injection position, the other pressure jacket is in a position in which an associated syringe can be rear-loaded. Subsequently, when injection of contrast media from the first syringe is completed, the turret is rotated to move the first syringe to an unloading-loading position, with the second pressure jacket and the syringe concurrently being moved into the injection position.
In the apparatus disclosed in the '980 patent, a drive member of the angiographic injector can be drivingly connected to, or disconnected from, a plunger of a syringe at any point along the path of travel of the syringe plunger by a releasable mechanism. However, for the releasable mechanism to correctly operate, the syringe plunger must be properly oriented to mate with the injector piston. Further, during loading of the syringe on the injector, the syringe must be correctly aligned within a respective pressure jacket to allow the syringe plunger and the injector piston to connect to and disconnect from each other.
An improved apparatus over the '980 patent apparatus is disclosed in U.S. Pat. No. 5,383,858, issued to D. M. Reilly et al. on Jan. 24, 1995, and entitled “Front-Loading Medical Injector and Syringe for Use Therewith,” which is also assigned to the same Assignee as the present application. In the apparatus described in the '858 patent, the syringe is front-loaded onto, in at least one embodiment, a pressure jacket-less injector, overcoming one of the drawbacks of the '980 patent injector apparatus.
The injector described in the '858 patent has a first release mechanism for attaching and releasing the syringe from the injector. In addition, the apparatus includes a second release mechanism that engages and disengages the injector piston from the syringe plunger. Upon rotation of the syringe, the syringe is attached to or released from the injector and, simultaneously, the plunger is attached to or released from the piston. The structure disclosed requires that the syringe be installed on the injector in a specific orientation so that the syringe can releasably engage the injector and, simultaneously, the plunger can releasably engage the piston. In addition, as with the syringe disclosed in the '980 patent, during assembly the syringe plunger must be correctly oriented within the syringe.
Another injector apparatus is disclosed in U.S. Pat. No. 5,300,031, issued to C. Neer et al. on Apr. 5, 1994, and entitled “Apparatus for Injecting Fluid into Animals and Disposable Front Loadable Syringe Therefor.” The '031 patent discloses various embodiments of a pressure-jacketed injector wherein a syringe is loaded into and removed from an injector pressure jacket through an opening provided in the front end of the pressure jacket. To retain the syringe within the pressure jacket, for example, during an injection operation, the front end of the syringe is locked to the front end of the pressure jacket. To correctly connect the syringe to the pressure jacket, the syringe may only be inserted into the pressure jacket in one orientation.
In each example discussed above, the syringe must be connected to the injector in a specific orientation to assure proper syringe mounting. Proper alignment is required to assure that the syringe may be operated properly during a medical imaging procedure. The required orientation, however, hinders rapid attachment and replacement of the syringe. The required orientation may also increase the manufacturing assembly cost and complexity of the syringe.
Accordingly, while the above injector and syringe apparatuses have proven effective, a need has arisen for a simpler front-loading medical injector. More specifically, to facilitate further the loading operation, a need has arisen for a syringe that can be easily connected to the injector without regard for the specific orientation of the syringe and/or syringe plunger. In addition, to simplify assembly of the syringe components, a need has arisen for a syringe with a plunger that does not need to be oriented in a specific relation to the barrel or base of the syringe. Furthermore, to minimize the time required to prepare an injector for an injection procedure, a need has arisen for injectors providing automated features.